Powers to monitor the UK's email and internet records will be of limited use in tackling serious crime, the government has admitted.
Home Office proposals for phone, email and internet records — including VoIP — to be kept for 12 months are expected to cost taxpayers up to £68m to set up and £39m per year to run.
Consultation papers released this week show the government wants to keep the "who", "when" and "where" of communication to "assist in the investigation, detection and prosecution of serious crime".
But a spokeswoman for the Home Office admitted the proposals would be of restricted use against organised criminals or terrorist organisations, as they were likely to disguise their communications.
Hiding internet or email traffic is relatively simple using methods such as logging on using unregistered 3G dongles, using third-party wi-fi networks and by sending email using a secure tunnel and proxy.
The spokeswoman suggested the information may be of more use against ordinary citizens and minor criminals.
She said: "The serious criminals may be far more savvy than your normal Joe Blow and the information we collect [for them] is not going to be of the same calibre."
But she said the measures would be worth it if they were to provide evidence that helped convict even one person suspected of a "serious crime".
The legislation would mean hundreds of public bodies licensed under the Regulation of Investigatory Powers Act — including local councils, health authorities and government agencies — will have access to the communication information.
As of last September telecoms providers must keep all text and phone-call records between six months and two years under an EU directive, and this is to be rolled out to include all online traffic by 2009 at the latest. This legislation would bring the UK in line with this requirement.
The Internet Services Providers Association said it welcomed proposals to reimburse ISPs for the cost of retaining data but was reserving comment ahead of its response to the consultation on the legislation, due to end in October.
Information commissioner Richard Thomas recently spoke out against plans to retain communications records in a centralised database.